COMMERCIAL LI M E
IN DADE COUNT
John D. Campbell, Hugh C. Whelchel,
Seymour Goldweber, Fred P. Lawrence
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Circular 237 June 1962
AGRICULTURAL EXTENSION SERVICE
University of Florida, Gainesville, Florida
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SOIL PREPARATION ..........
STOCK AND SCIONS ........
PLANTING ............ ... .
Young Trees ..........
Bearing Trees ........
INSECTS AND DISEASES ...
IRRIGATION .......... ...
PRUNING .............. ...
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The cover scene is typical of new techniques used in planting container-
grown Persian lime trees in Dade County.
COMMERCIAL LIME PRODUCTION
IN DADE COUNTY
JOHN D. CAMPBELL, HUGH C. WHELCHEL, SEYMOUR GOLDWEBER
AND FRED P. LAWRENCE *
The popularity of the Persian lime has become widespread in
recent years, and many new plantings are being established in
Dade County and other areas of southern Florida.
In the past, the cultural practices of lime production have
been very similar to the production of other citrus. In recent
years, especially in Dade County where conditions differ consid-
erably from those in other citrus producing sections, there has
been a trend, based on trial and error, to develop cultural prac-
tices especially adapted to limes on the rocky soils there. This
circular is an attempt to set up a cultural schedule using existing
research as a guide and incorporating some of the techniques used
successfully by lime growers in Dade County.
The Persian lime is much more susceptible to cold injury than
most other citrus. This, to a large extent, accounts for the fact
that approximately 80 percent of the Florida lime crop is pro-
duced in Dade County, although lime plantings have done well in
the lower ridge section and on the east and west coasts of south-
ern Florida. Even in Dade County, where the weather is favor-
able, certain precautions are advisable in selecting land for a
lime planting. The slope of the land should be such that cold air
will drain away from the planting. Cold air should not drain to
the planting or collect in local pockets within the planting.
Relatively high, well-drained land is preferred. Much of the
pine or rock land in south Dade County is well suited for lime
plantings. In planning for a new grove it is a good idea to check
the history of the groves in the particular area. If they have
been in steady production in spite of severe cold weather, the
area is probably quite warm. On the other hand, if there are few
groves, and some of these are spotty and show effects of having
been damaged severely by cold in the past, the adaptability of
the area might be questionable. However, almost every lime
* Campbell, Dade County Agricultural Extension Agent.
Whelchel, former Assistant Dade County Agricultural Extension Agent,
now St. Lucie County Agricultural Extension Agent.
Goldweber, Assistant Dade County Agricultural Extension Agent.
Lawrence, Citriculturist, Florida Agricultural Extension Service.
grove in Dade County has been injured in varying degrees by se-
vere cold waves in the past.
In addition to the relative elevation of the land, cultural
practices seem to be a major factor concerned with resistance to
Land to be planted to limes is first cleared of all trees and na-
tive growth by bulldozers. This material is pushed into piles,
where it is burned.
The plowing operation is then started. This is done with a
large, wedge-shaped plow that is attached to the front of a crawl-
er tractor. A cut is made 1 to 2 inches deep and 2 to 3 feet wide,
breaking up the limestone rock and rolling it out to either side.
The rollout from one cut covers the cut made before, much the
same as with conventional plowing.
The rollout is passed beneath the tracks of the large tractor,
which helps to crush the newly cut rock. This operation is con-
tinued over the entire field, then repeated at a right angle, and a
third time at a different angle. Each time the cut is deepened
1 to 3 inches. After a total of four or more cuts have been made,
6 to 9 inches of top soil have been worked.
Figure 1.-A chisel on a crawler tractor may be used to scarify the
heavy lime rock soil preparatory to planting young lime trees.
After the tree rows are marked off in both directions, the
scarifying blade or rock plow is replaced with another plow, a
trenching plow, for the purpose of plowing trenches in which the
trees will be planted. Repeated cuts are made along the desig-
nated tree rows until the pre-determined depth of the trench is
reached. These trenches may vary in cross section from a
trench 12 to 14 inches wide and up to 20 inches deep to trenches
which are as wide as 40 inches and 12 inches deep. Most grow-
ers prefer the deepest trench possible and will accept the narrow
widths to attain depth. When the tree row trenches are com-
pleted, the cross trenches are plowed at right angles to the tree
rows. These trenches are spaced at the distance which has been
pre-determined for the spacing of trees in the rows.
Figure 2.-A tractor with an auger is often used to bore the
holes for planting young lime trees.
After trenches have been plowed, they are filled and covered
with the soil which has been plowed out of the trenches. The
common practice is to level cross trenches completely but to
leave a ridge from 6 to 12 inches high and about 3 feet wide run-
ning the length of the tree row trenches. This leaves an abund-
ance of loose soil for the planting operation.
The purpose for trenching as opposed to the older systems of
dynamiting or "grubbing out" holes for trees is to provide an
area of broken rock through which the roots can attain some
depth in the soil. The trenching operation also often exposes
solution holes into which roots eventually find their way. Tree
holes are prepared either with an auger on the back of a tractor
or by hoeing out the loose soil by hand.
STOCK AND SCIONS
Persian limes are grown on several different varieties of root
stocks, including rough lemon, Cleopatra mandarin, sweet or-
ange, sweet lemon, and grapefruit. Rough lemon is by far the
most popular, with approximately 64 percent of the plantings in
the state on this stock. Sweet orange has also shown some prom-
ise in the last few years.
Another method of establishing a new lime tree that has be-
come popular in this section is by marcotting, often referred to as
air layering. In comparison to the budded tree, the marcott tree
seems to possess rather exceptional vigor and fruiting capacity,
and production begins at an earlier age after planting than is the
case with the budded tree. Since marcotting has been used com-
mercially only in recent years, the characteristics and behavior
of older trees propagated by this method are not known.
Marcotted trees, particularly those from certified clones, thus
far have shown considerable promise for the above stated rea-
sons. However, it should be pointed out that high water tables
have caused serious root rots on these self-rooted individuals,
and present recommendations would necessarily state that they
not be planted in areas subject to flooding or critical water tables.
In addition, observations seem to indicate that the marcotted
trees also are more subject to magnesium deficiency than trees
on rough lemon rootstocks.
Young lime trees can be planted at any season of the year.
However, trees planted in spring just before the rainy season
will require less care from the standpoint of applying water.
Trees should be watered immediately after planting and at least
twice a week for two to three weeks. Watering at intervals of
two or three weeks should be continued for the next four or five
months, depending on rainfall.
Persian limes in Dade County are planted 12 to 25 feet apart
in rows that are 18 to 25 feet apart, thus giving from 69 to 200
trees per acre. It should be kept in mind that trees planted too
close will become overcrowded as they become older. When this
condition occurs, it is very difficult to maintain the grove in good
condition or to produce high quality fruit unless the trees are
The number of lime trees planted per acre in recent years has
increased to as many as 200 trees per acre. In these cases hedg-
ing or pruning will be a necessity. Close planting, with hedging
or pruning, is recommended to increase the fruit bearing surface
on a per acre basis and to maintain this high yielding fruiting
surface throughout the year.
Figure 3.-At left, a marcotted, potted lime tree is removed from the
pot for planting. At right, the tree is set in planting position. Measuring
for depth can be done in this manner, but a planting board is customarily
Securing young lime trees from the nursery is a step that
should receive special attention. In Dade County, because of the
rocky condition of the soil, limes are propagated in pots or cans.
Care should be taken to select trees which are propagated from
older trees that are known to be disease free and to yield good
crops. It is also important to avoid trees which have become pot-
Staking the individual tree holes is no longer a common prac-
tice. Tree rows are staked at both ends, with cross rows staked
tice. Tree rows are staked at both ends, with cross rows staked
the same way as prior to plowing. A center line of stakes is
placed in both directions prior to planting. When trees are plant-
ed, they are "sighted-in" in both directions. The person planting
the tree lines it up with the middle stake marking the trench and
the stake at the end of the row. A hole is then dug. If there is
not sufficient soil in the scarified portion around the tree roots,
the hole should be enlarged and some soil placed in the opening
before the tree is planted. It is recommended that a pound of a
natural organic fertilizer be mixed into the soil in the bottom of
the hole prior to planting. The placement of the fertilizer ap-
pears to stimulate early growth of the young tree. The container
is then removed from around the roots of the tree, and the con-
tents, undisturbed, are placed in the hole. Care should be used
to make certain that the tree is not planted too deep. The tree
Should be planted no deeper than it was in the pot, and the bud
union (if a budded tree is used) should always be well above the
surface of the soil. The scarified soil is then pulled back around
the root system, watered, and pressed down so as to make a firm
planting. Ten to fifteen gallons of water is applied at the time
of planting. This helps to pack the soil and eliminates air
pockets around the roots.
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Figure 4.-A young lime grove is shown three months after
planting in oolite-limerock soil.
It is advantageous to place a mulch of weeds, shavings, paper
bags, or organic material around the young trees immediately
after planting. The mulch will greatly increase moisture reten-
tion and protect the rooting area from the direct rays of the sun.
In planting marcotted trees, a depth of soil of about 6 to 9
inches above the crown roots of the young tree is highly desirable
to support the trunk of the young tree in the ground. The roots
of the young marcotted tree do not have the ability to support
the tree until they have formed a considerable secondary root
system. Staking and tying are occasionally necessary to support
these trees against wind which usually is responsible for breaking
off the young roots on the marcotts. Growers are cautioned
against packing the soil around the stems when planting young
marcotted trees. This, too, may be responsible for breaking off
roots and causing ultimate death of the tree.
An application of 12 pound per tree of a 6-6-6-3 fertilizer
should be made approximately a month after planting. Fertili-
zation at intervals of four to six weeks should be continued,
gradually increasing the rate to 1 pound per application by the
end of the first year. The second year the application should be
increased gradually to 2 pounds per application. In the third and
fourth years the same analysis is used, but the applications
should begin with 2 to 3 pounds and be made at eight-week in-
tervals, increasing the rate gradually by 1 to 112 pounds during
the year. During the first few years the primary concern should
be in forming large, healthy trees. Fruit produced during these
early years should be of secondary importance, and all effort be
directed toward growth rather than production.
Secondary elements such as copper, zinc, and manganese are
best supplied to the tree through a spray. In most cases it is ad-
visable to make two applications per year for the first two to
three years, using a spray containing 3 pounds of zinc sulfate, 3
pounds of copper sulfate, 3 pounds of manganese sulfate, and 2.3
pounds of hydrated lime per 100 gallons of water, or equiva-
lent amounts of zinc, copper, and manganese in neutral form.
There is a wide variation in the amount and analysis of fer-
tilizer used in the lime industry. Through evaluation of the pro-
grams of several progressive growers and interpretation of the
limited research information available, the following recommen-
dations are suggested.
A fertilizer mixture containing nitrogen, phosphorus, potash,
and magnesium in a ratio of 1-1-1-1/2 is recommended for a bal-
anced nutritional program. This ratio is represented by a 6-6-6-3
fertilizer. Applications should be made four times a year, usu-
ally in January or February, April or May, July, and October.
The rate per tree will vary with the size and production of the
tree. A tree producing two boxes of fruit per year should re-
ceive 5 to 7 pounds per application, and a tree producing five
boxes should receive 6 to 8 pounds per application. For trees 15
to 25 years old with four-to six-box yields, the poundage should
run between 13 and 15 pounds per tree per application.
Figure 5.-Dr. C. D. Leonard of the Citrus Experiment Station stands
by a four-year-old Persian lime tree, depicting the outstanding growth of
a properly fertilized grove.
In older bearing groves where there is an accumulation of
phosphorus, other formulas such as 8-0-8-4 and 10-0-10-5 may be
substituted for one or more applications with satisfactory results.
If only one or two applications are substituted, apply one as the
fall application, and if desired, another as the winter application.
Where these higher analysis fertilizers are used to replace the
6-6-6-3, the poundage should be reduced to supply the same
amount of nitrogen per tree. For example, a five-box tree re-
ceiving 13 pounds of 6-6-6-3 should receive 8 pounds of 10-0-10-5.
Many growers have successfully supplemented the fertilizer
program with one or more applications of water-soluble nitrogen
in the spray or irrigation water. Water-soluble nitrogen can be
added when insect or disease sprays are applied. For poundage
recommendations, refer to instructions on the manufacturer's la-
INSECTS AND DISEASES
There are several insects that attack limes in this section.
Red scale, purple scale, rustmite, red spider, and aphids are the
major insects for which controls are often necessary.
Scale insects often build up to a population that warrants con-
trol. Where control of scale is desired, a spray containing 1.3
percent oil or a 15 percent wettable parathion powder at 11/2
pounds per 100 gallons of water or a mixture of 0.7 percent oil
and 1 pound of 15 percent parathion per 100 gallons of water is
Rust mites are serious pests of limes. Buildups in the mite
population should be prevented. Rust mites are readily con-
trolled with wettable sulfur at a rate of 8 to 10 pounds per 100
gallons of water or Zineb at /2 to 1 pound per 100 gallons.
Aphids are not considered important commercially except oc-
casionally in new plantings of young trees. Nicotine sulfate
as a 3 percent dust or as a spray of 1 pint per 100 gallons of
water is considered a good aphicide. TEPP and parathion may
also be used for control of aphids. More detailed and additional
information can be obtained from the county agent's office.
There are many diseases common to Persian limes in this
area. Most are transmitted through diseased budwood or prop-
agating material, some by insects and other methods.
In Dade County most of the lime groves are planted on rock
land, which poses cultivation and weed control problems. After
the land is initially prepared and the trees planted, there is rela-
tively little cultivation such as discing or plowing. Weeds are
controlled by mowing or dragging. In this latter practice, a
heavy metal drag is pulled over the surface of the rocky soil,
thus agitating the top layer of rock and soil and destroying the
weeds. Dragging is practiced mostly in young groves where
clean cultivation is desired.
Mowing is the most popular form of weed control in older
groves. In this practice the grove should be mowed closely dur-
ing the dry winter months both to prevent possible damage by
fire and to reduce the competition for moisture. It will also al-
low free air drainage on cold nights. After the rainy season be-
gins, it is generally considered good practice to let the native
cover grow. This will give a good ground cover and serve as a
source of organic mulch to preserve moisture and to be incorpo-
rated into the soil. Mowing is also done during the picking oper-
ation to allow picking crews access to the tree. Hoeing or weed
pulling is necessary around young trees and in areas inaccessible
to mowing equipment.
The months of January, February, March, and April are often
very dry in this section. During this period and other occasional
dry spells, it becomes necessary to supply water to the trees to
insure the maximum growth and crop yield. This is done mostly
by overhead irrigation. Wells drilled to a depth of 20 feet will
usually supply sufficient quantities of water for irrigation. These
wells are 6 to 8 inches in diameter and usually are without cas-
ings. The low cost of well-drilling accounts for the practice of
drilling many wells in individual groves and irrigating with port-
Figure 6.-"Jury-rig" on a tractor supplies irrigation from a shallow
well. The common practice is to have two or three shallow wells on each
five-acre block, and to irrigate with a pump and gun similar to the rig
shown. This eliminates the need for expensive pipe and labor.
able high pressure pumps and guns which cover one or more
acres at one time, rather than using one well and portable pipe
to distribute the water throughout the grove.
In the citrus producing areas of the state it is often de-
bated whether or not irrigation pays off from an economic stand-
point. In this section, because of the unique system of irriga-
tion, the acutal cost of irrigation is much less than in the other
citrus producing sections. Because the rock soil will not retain
moisture over a period of time, it is recommended that arrange-
ments be made for irrigation during extended dry weather if
maximum production is desired.
Pruning is one of the most important operations in mainte-
nance of lime groves. Yet many growers give it little or no con-
sideration. Perhaps this is partly due to the fact that when
pruning is neglected there is no apparent effect on the present
crop, as would be the case with spraying and fertilizing. How-
ever, over a period of years, failure to prune can be responsible
for a considerable amount of damage, both in loss of marketable
fruit and loss of trees through damage by disease and insects.
It is a good practice to go through the grove once a year and
prune out any dead wood or suckers, pull out vines, and remove
any tree that is of little commercial value. This can be done
during the early spring, after the cold weather is over and before
heavy picking begins.
Lime trees that are set close will overlap or grow together
as they get older, making cultural operations and harvesting a
problem. This situation also causes a dense canopy, shading
much of the fruit and causing it to be of light color. Trees of
this type should be pruned or hedged back to allow easy passage
of equipment. This will also allow for the penetration of sunlight
and a maximum production of high quality fruit.
The authors gratefully acknowledge the valuable assistance
of W. R. (Bill) Llewelly, former Assistant County Agent, Dade
County; Jack T. McCown, Assistant Citriculturist; and a number
of Dade County lime growers for their helpful suggestions, many
of which are incorporated in this circular.
COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
Agricultural Extension Service, University of Florida,
Florida State University and United States Department of Agriculture, Cooperating
M. O. Watkins, Director